Variable capacity reciprocating pump



June 6, 1950 w. T. STEPHENS VARIABLE CAPACITY RECIPROCATING PUMP 2 Sheets-Sheet 1 Filed Feb. 1, 1945 mm a 0m ms wN h n O P a wm NQ June 6, 1950 w. T. STEPHENS VARIABLE CAPACITY RECIPROCATING PUMP 2 Sheets-Sheet 2 Filed Feb. 1, 1945 HNH Patented June 6, 1950 William .T. Stephens, Cleveland, Ohio, assignor, by'mesn'e' assignments, to Hydraulic Equipment Company, "Cleveland, Ohio, a corporation of Ohio Application February 1, 1945, Serial No. 575,699

18Glaims:

This invention" relates' to *reciprocating or plunger'pumps'and particularly to pumps of that type for delivering liquids under relatively high pressure and adapted toautomatica'lly change from high toilowcapacity whereby higher pres sures may be obtained without materially greater effort.

.Thepump of. the present invention is particularlydntended forman'ual operation-in the manipulation of tools such as hydraulic vises', arbor presses and the like and" it isthe purpose of the present inventiont'o materially simplify the con struction and operation of these devices.

It is, therefore, an object 'oftheinvention to provide a pump assembly including a reservoir.

The apparatus'o'f the present invention includes a manually operable pump intended for'supplying relatively small quantities of liquid at high pressure for the operation'of such devices as arbor presses; hydraulic vises and various other tools of a similar nature. Theapparatus is selfasubmerged pumpa'nd a release valvetegether 1 with means for automatically shifting the pump from large to small capacity.

More particularly, it is one object of the invention to provide a pump having a piston rod of substantial area operating in the inlet side of the pum cylinder together with a return valve between the discharge and inlet sides of the pump cylinder subject to operation by increase in discharge pressure for the pump.

A further object of the invention is to provide 3 in a pump of the large connecting rod type of an auxiliary'liquid inlet on" thedischarge side of the piston"which auxiliary valve functions only on' high capacity operation of the pump.

Asa further important feature or the invention there is contemplated the arrangement oi a du'al'transfer valve and return valve housed within the piston.

Other and further objects and features of the invention deal particularly with simplification of construction, the reduction of machine work and the lowering of cost of pump assemblies.

It will be clear as the description proceeds that additional objects and features of the invention are incorporated in'tl'ie disclosure which illus- Fig. 2 is a longitudinal vertical central section through a pump assembly constructed as described herein, and

Fig. 3 is a fragmentary section similar to Fig. 2 but on an enlarged scale for illustrating the actual pump and valve mechanism.

contained and can be used without additional valvesor accessories fori'oper'ating' any small capacity, singleacting'hoist or rain of the spring or load returnedvariety whenco'upled' to the ram cylinder by means of a single pipe or conduit.

The assembly includes a reservoir for a suitable quantity of liquid, a pump mechanism and its valves, a relief'valve'to' preventexcesspressure from damaging any of the equipment and arelease valve whereby theliquid may be discharged from the toolram'soitliat the latter can return to its initial position under the action of its springor load. For convenie'nce'theassembly is arranged for'mounting on the' fl'o'or or base of amachine and thepump is'operated by a foot pedal, the downward movement of which provides the delivery stroke. The pedal is returned to position for further operation by a spring'conveniently inc'orporatedin' thepump cylinder. The liquid used with the'p'ump is preferably a'lubricating oil or like material which lubricatesand protects the working parts.

Referring to the drawings and first 'to Figs. 1 and 2, it will be seen that the assembly is incorpor'ated in a single casting or housing E8 having near the top a reservoir compartment H supported by laterally spaced legs 52 and spaced integral feet l3 each of which is perforated at several positions, as shown, to receive suitable hold-downbolts.

' The reservoir H is oi'suitabl'e capacity to hold the quantity of oil desired for the operation of whatever tool is to be connected to the pump assembly; It is "completely closed except for a filler opening'covered' byca'p t5 of the screw type havinga' vent aperture 15 for the entrance and egress of airduring the operation. A'dust cap I! with a pendulousskirt'protects'the vent. For convenience in manufacture" the-casting is providetl with a re entranvpa'rt aboveand between thespaced legs and adapted to be'submerged in the oil in the reservoir The whole casting is here provided with a vertical bore 20, the upper portion of Which'is threaded toa'ccommodate the filler cap and the spaced lower portion of which constitutes the pump cylinder or barrel.

The top' of the cylinder is closed off from the upper portion of the reservoir by means of a cylinder head 2'! of inverted cup shape having a close fit in the cylinder walls and adapted to be secured therein by a set screw (not shown) whose inner end is received in the circumferential groove 22. The opposite end of the cylinder bore is closed by a head 24 likewise having a close fit within the bore and adapted to be held in position by tapered drive pins 25. Each of the cylinder heads is provided with a circumferential packing 2B of the expansible type to prevent leakage. The piston which works between the two heads is shown generally at 28 and is mounted by means of threads 28 on the upper end of a piston rod 33 of substantial diameter provided with circumferential grooves 31 to receive flexible packings adapted to provide a tight working fit in the bore 32 in the lower cylinder head 24.

The spaced legs 12 provide convenient mounting means for the pivot pin 34 for the lever carrying the operating pedal 35. As seen in Fig. 1 this pivot 34 is a substantial pin fitting in transverse openings in the legs where it is secured by means of cotters. The cast pedal assembly includes a drilled boss 31 journalled on this pin 34. The opposite end of the pedal lever is bifurcated as at 38 and mounted between the furcations is the roller 39 journalled on pin 49 extending through these members. This roller is directly beneath and contacts the flat bottom surface of the piston rod so that pressure downwardly on the pedal lifts the rod and with it the piston 28. The pedal is returned to the operating position shown in Fig. 2 by means of the heavy helical spring 52 mounted between the upper end of the piston and the underside of the cylinder head 2|.

The cylinder bore 26, aside from coming out through the bottom of the casting and entering into the main portion of the reservoir ll, intersects a lateral chamber 44 just below the upper head and a lateral inlet chamber 45 extending just above the lower head. Where it extends to the left, the upper lateral chamber 44 intersects a vertical bore 45 which is counterbored above and intersects the extension 4! of the reservoir. A relief valve 48 is mounted to close the bore 46 and is positioned by means of a spring 49 ad-' justably tensioned by means of a threaded rod 59 mounted in the screw cap closing aperture 52 in the top wall of the reservoir. Suitable lock and sealing means close off the end of the adjustable rod Ell in a conventional manner. It will be seen that the relief valve 48, which is noncircular in cross-section and a conical end to engage with the seat at the junction of the large and small bore 46 will be lifted when excess pressure occurs in 44, or above the piston, and will release the liquid causing this pressure into the reservoir.

The inlet chamber 45 connects to the space beneath the piston 28 at all times by virtue of the piston being slightly elevated on spaced annular segments 53 projecting up from the lower cylinder head 24 as best seen in Fig. 3. This chamber 45 is adapted to be connected to the lower chamber 55 of the reservoir by means of a straight vertical bore 56 which houses the inlet valve plunger 51. This plunger is generally of the type which includes a longitudinally bored cylindrical stern 58 which has a close working fit in the bore 55 and a conical head 59 which seats at the junction of the bore 55 and the top wall of the com partment 45. Lateral openings 6!] connect with the central bore so that when the valve is opened to the extent that these openings clear the bore fluid can flow freely through the central bore of the stem and out through the lateral openings 60 and beneath the raised head affording passage from 55 to 45. This opening is automatically effected when the pressure is reduced in 45 by the lifting of the piston 28. The valve 5'! which will hereinafter be termed the inlet valve for the pump is held closed by means of a suitable spring 6! engaging over a pin 62 on the head of the valve and supported at the opposite end by pin 63 integral with the inner end of a screw plug 64.

The discharge valve for the pump is shown at 66 and is of identical construction and size to the inlet valve and is mounted in a bore 61 which connects the right end of lateral chamber 44 with the outlet chamber 68. This valve is opened when pressure in the upper portion of the pump chamber is greater than pressure in the chamber 68 and is maintained closed by helical spring 69. The chamber 63 is connected to perforated boss it on the outside of the pump casting as seen in Fig. 1, this boss being threaded to receive a suitable pipe or conduit leading to the machine to be operated.

The upper cylinder head 2| is of inverted cuplike form with an inner compartment 12 which houses the head of an auxiliary or supplemental inlet valve '53 of identical construction to the inlet and discharge valves of the pump. The upper end of this valve is open to the reservoir but the valve is maintained closed by means of spring '55 abutting against the upper face of perforated washer 75 held in position against the underside of the upper cylinder head by means of the main pump spring 42.

The lower end of this pump spring bears on the top of the piston 28 in an annular area surrounding an upward projection 18. This upward projection houses the upper end of a valve chamber formed by an axial bore '59 in the piston as an extension of the one receiving the screw threaded end 29 of the piston rod. This bore is connected by a small opening through the top of the piston into the upper pump chamber. The bore (9 houses the piston transfer valve 8|. This valve comprises a length of rod with longitudinal grooves and intermediate ridges to provide a close sliding fit in the bore. The lower end of the rod is tapered to provide a conical valve structure for cooperation with a seat at the junction of the upper end of the piston rod and a central bore 82 therein. This bore is connected to the surface of the piston rod just beneath the lower face of the piston by means of radial bores 83. The valve BI is normally closed by means of a spring 84 engaged between the upper end of the same and the underface of the head of the piston.

The normal pumping operation at relatively low pressures may now be described. Assuming the reservoir H to be filled with suitable liquid and with the filler cap open, the pedal 35 is depressed, lifting the piston and reducing the prersure in the inlet chamber 45. Atmospheric pressure on the liquid in the reservoir then forces inlet valve 5! open and liquid from the reservoir flows into 45 and into the space at the lower end of the pump cylinder now evacuated by the piston. During the initial or priming operation it is preferred that the supplementary inlet valve :3 be depressed to open position by means of a suitable tool inserted through the filler opening of the reservoir. This permits the escape of air trapped in the pump mechanism and also permits liquid which is normally above the level of the opening of this valve to flow into the pump chamber to assist in filling it on the down stroke.

fashioned into a foot engaging portion IN. A short distance above the pivot the lever is equipped with a transverse pin I22 on which is mounted a roller I23 in a position to contact the end of the plunger H when the release lever is pressed with the foot.

It will be seen that after the tool or the like has been operated it will be held in position as long as desired by the action of the discharge valve 66 and the release valve I03, both of which are tight. When it is desired to release the tool, pressure is applied to the release lever I H in the amount desired to open the release valve I03 and permit return of the liquid from the operated mechanism into the reservoir at a rate determined by the amount of opening of the release valve. It will be appreciated that with tools like hydraulically actuated vises it is not always desirable to have the jaws move apart to their maximum under the action of their spring. Movement of perhaps less than of an inch will usually be sufficient to release the work. This can readily be accomplished by the variable flow adjustments of the release valve, which permit the release of desired quantities of liquid, with rapid and sensitive control eliminating the need for a great deal of pumping at each operation of the tool. Furthermore the two ranges of the pump permit of rapid initial adjustment of a vise (for instance) and then the application of high pressure to finally clamp the work.

I claim:

1. In a liquid pump of the type described, in combination, a housing having a pump barrel and inlet and discharge valves asociated with opposite ends thereof, a piston reciprocable in said barrel and having a piston rod on the inlet side thereof, and discharge-pressure responsive means adapted to connect the discharge and suction sides of the piston in the space between said valves when the said pressure exceeds a predetermined value, whereby the liquid on the discharge side of the piston in excess of the displacement of the piston rod is returned to the suction side during each pumping stroke.

2. In a liquid pump of the type described, in combination, a housing having a pump barrel and inlet and discharge valves associated with opposite ends thereof, a piston reciprocable in said barrel and having a piston rod on the inlet side thereof, and discharge-pressure responsive means adapted to connect the discharge and suction sides of the piston within the volume defined between said valves when the said pressure exceeds a predetermined value, whereby the liquid on the discharge side of the piston in excess of the displacement of the piston rod is returned to the suction side during each pumping stroke. said discharge-pressure responsive means being mounted in the piston.

13. In a liquid pump of the type described, in combination, a housing having a pump barrel and inlet and discharge valves associated with opposite ends thereof, a piston reciprocable in said barrel and having a piston rod on the inlet side thereof, a transfer valve in said piston for the passage of liquid from the suction to the discharge side of the piston, and discharge-pressure responsive means adapted to connect the dis charge and suction sides of the piston when the said pressure exceeds a predetermined value, whereby the liquid on the discharge side of the piston in excess of the displacement of the piston rod is returned to the suction side during each pumping stroke, said discharge-pressure respon- 8 sive means being mounted in said transfer valve.

4. In a liquid pum of the type described, in combination, a housing having a pump barrel, an inlet valve at one end thereof and a discharge valve at the opposite end thereof, a piston reciprocable in said barrel and having a piston rod on the inlet side thereof, discharge-pressure responsive means adapted to connect the discharge and suction sides of the piston when the said pressure exceeds a predetermined value whereby the liquid on the discharge side of the piston in excess of the displacement of the piston rod is returned to the suction side during each pumping stroke, and a supplemental inlet valve associated with the discharge side of the piston.

5. In a liquid pump of the type described, in combination, a housing having a pump barrel, an inlet valve at one end thereof and a discharge valve at the opposite end thereof, a piston reciprocable in said barrel and having a piston rod on the inlet side thereof, discharge-pressure responsive means adapted to connect the discharge and suction sides of the piston when the said pressure exceeds a predetermined value whereby the liquid on the discharge side of the piston in excess of the displacement of the piston rod is returned to the suction side during each pumping stroke, a supplemental inlet valve associated with the discharge side of the piston, a liquid reservoir associated with said pump and providing a liquid level above the barrel thereof, said barrel being vertical with the discharge end at the top and said supplemental inlet valve being accessibly positioned for manual opening to bleed the system of air during initial filling with liquid.

6. In a liquid pump of the type described, in combination, a housing having a pump barrel, an inlet valve at one end thereof and a discharge valve at the opposite end thereof, a piston reciprocable in said barrel and having a piston rod on the inlet side thereof, discharge-pressure responsive means adapted to connect the discharge and suction sides of the piston when the said pressure exceeds a predetermined value whereby the liquid on the discharge side of the piston in excess of the displacement of the piston rod is returned to the suction side during each pumping stroke, a supplemental inlet valve associated with the discharge side of the piston, a liquid reservoir associated with said pump and providing a liquid level above the barrel thereof, said barrel comprising a vertical bore in said housing, a head closing the upper end of said bore and housing said supplemental inlet valve and a spring between said head and the piston to return the latter after a pumping stroke.

7. In a liquid pump of the type described, in combination, a housing having a reservoir for liquid, a vertical pump barrel immersed in said reservoir and having an inlet valve connected to the lower end and a discharge valve connected to the upper end, a piston reciprocable in said barrel and having a piston rod on the inlet side thereof, a transfer valve in said piston, a discharge-pressure responsive means adapted to connect the discharge and suction sides of the piston when the discharge pressure exceeds a predete mined value whereby the liquid on the discharge side of th piston in excess of the displacement of the piston rod is returned to the suction side during each pumping stroke, a head closing the upper end of said barrel and a supplemental inlet valve extending through said head and having its upper end immersed in the liquid in said reservoir.

theupp'er' eri'djahigh' pressure ch-amber'for connection'to a devicehperatedby the liquid under pressure,- said discharge valve opening ihto said chamber, a pistonreciprocable in said barrel and having a piston'i'od on the inlet side thereof, a transfer valve'in said pistons discharge-pressure responsive means adapted to connect-the discharge-and suction sidesor" the piston when the discharge pressureexceeds a predetermined value whereby the liquid on the discharge side of the piston in excess of the displacement of the piston rod is returned to the suction side during each pumping stroke, a head closing the upper end of said barre-l, a supplemental inlet valve extending through said head and'having its upper end-immersed in the liquid in reservoir,- and a manually operable release valve adapted to connect said high-pressure chamber to thereservoir for the returnof-the liquid from the operated device,

9. In an apparatus of the type-described, in combination, a casting providinga reservoir and an immersed pump housing, a vertical bore through the housing and reservoir top, a head in the housing bore separating it from the reservoir, and providing a pump barrel, 2, piston reciprocable in said barrel and having a piston rod on the suction side thereof, a lower head drilled to pass said rod, a side chamber adjacent each head and connected to the barrel, an inlet valve opening from the reservoir into the lower chamber, a discharge valve opening outwardly from the upper chamber, a transfer valve in said piston and discharge-pressure responsive means adapted to connect the discharge and suction sides of the piston when the said pressure exceeds a predetermined value whereby the liquid on the discharge side of the piston in excess of the displacement of the piston rod is returned to the suction side during each pumping stroke.

19. In an apparatus of the type described, in combination, a casting providing a reservoir and an immersed pump housing, a vertical bore through the housing and reservoir top, a head in the housing bore separating it from the reservoir, and providing a pump barrel, a piston reciprocable in said barrel and having a piston rod on the suction side thereof, a lower head drilled to pass said rod, 3, side chamber adjacent each head and connected to the barrel, an inlet valve opening from the reservoir into the lower chamber, a discharge vaive opening outwardly from the upper chamber on a horizontal axis, a high pressure chamber supplied by the liquid from the discharge valve, a release valve connecting said high pressure chamber to the said reservoir, said release valve movable in a bore co with that, for the discharge valve, a transfer valve in piston and discharge-pressure responsive means adapted to connect the discharge and suction sides of the piston when the said pressur exceeds a predetermined value whereby the liquid on the discharge side of the piston in excess of the displacement of the piston rod is returned to the suction side during each pumping stroke.

11. In an apparatus of the type described, in combination, a casting providing a reservoir and an immersed pump housing, a vertical bore through the housing and reservoir top, a head in 10 l 1 the housing b'ore' separaaugiirfrorri the: reservoir; andproviding a "pump'barr'el, a; piston recipro cable in said'barrelahd-having a piston rod on thsuction' 'side' thereof, a lower head drilled to' pass said rod, aside chamber adjacent each head and connected to the-barrel, an inlet valve openingfrom thereservoir intothe lower chamber, a discharge valve opening outwardly from theupper chamber on a horizontal-ants, a -high pressure chamber-supplied by liquid from the discharge valve, a release valve" connecting said high pressure chamber to the said-reservoir, said release valve movable in a bore coaxial with that for the-"disc"harg van-cyatransfer valve in said piston and a pump chamber pressure responsive reuse valve adaptedto connect the upper side chamber to the reservoir.

12'. an apparatus" of the type described, in combination, a casting providing' a reservoir and a .-pu mp housing positioned to-be immersed'in the liquid. in the reservoir; a vertical bore through the housing and-reservoir top, a top head in the housing-boreseparating it-from the reservoir; and providing a pump-barrel, a piston *reciprocable in said barrel andhaving a' piston rod on thesuction ide*--thereof,--a'- lower headdrilled to pass said rod; aside chamberconnected to the barrel ad'- j-acent each head, an inlet valveopening from the reservoir into the lower chamber, a discharge valve opening outwardly from the upper chamber, a high pressure chamber supplied by liquid from the discharge valve, a release valve adapted to connect said high pressure chamber to the said reservoir, a transfer valve in said piston, a supplemental inlet valve extending through the top head whereby it is available for manual opening through the filler bore in the reservoir top and a closure cap for said reservoir.

13. In a liquid pump adapted to automatically change its displacement with discharge pressure changes comprising in combination, a pump barrel having an inlet valve at one end and a discharge valve at the opposite end, a piston, a piston rod at the inlet end of the barrel, a transfer valve in the piston adapted to close an aperture therethrough on the discharge stroke and a discharge-pressure responsive valve mounted in the transfer valve.

14. In a liquid pump adapted to automatically change its displacement with discharge pressure changes comprising in combination, a pump barrel having an inlet valve at one end and a discharge valve at the opposite end, a piston, a piston rod at the inlet end of the barrel, a transfer valve in the piston adapted to close an aperture therethrough on the discharge stroke, a discharge-pressure responsive valve mounted in the transfer valve, and a supplemental inlet valve at the discharge valve end of the barrel to supply a volume of liquid per stroke equal to the different displacements of the opposite ends of the piston.

15. In a liquid pump adapted to automatically change its displacement with discharge pressure changes comprising in combination, a pump barrel having an inlet valve at one end and a discharge valve at the opposite end, a piston, a piston rod at the inlet end of the barrel threaded into the piston, a chamber in the piston open to the barrel at the discharge end, a spring pressed valve plunger having a conical end, a passage in the piston rod providing access between the pump barrel at the inlet end and said chamber, said conical end cooperating to close said passage, and

11 a spring pressed valve in said valve plunger opening in the opposite direction thereto.

16. A liquid pump adapted to deliver against low pressure the full displacement of its piston and against higher pressure the displacement of its piston rod only, comprising in combination, a pump barrel, a piston in said barrel having a large diameter piston rod, a head closing one end of the barrel and passing said rod, an inlet valve delivering to the rod end of the barrel, a head for the opposite end of the barrel, a discharge valve and a supplemental inlet valve for said latter end, a transfer valve adapted to pass liquid from the rod side to the opposite side of the piston on the intake stroke and to close on the discharge stroke, and a valve sensitive to discharge pressure to connect the two sides of the piston when delivery is against excess pressure whereby only the rod displacement is effective for discharging liquid.

1'7. In a liquid pump, in combination, a barrel, a piston reciprocable in said barrel, a rod for said piston, heads for said barrel, one bored to pass said rod, separate inlet valves for the two ends of the cylinder, a discharge valve for the end of the cylinder free of the rod, and a transfer passage and valve connecting the barrel portions on opposite sides of the piston, said transfer valve opening automatically on the return stroke of the piston and the passage being continually open at both ends.

18. In a liquid pump, in combination, a barrel, a piston reciprocable in said barrel, a rod for said piston, heads for said barrel, one bored to pass said rod, an inlet valve for the rod end of the cylinder, a discharge valve for the opposite end of the cylinder, a transfer passage in the piston between the two ends of the cylinder, a check valve in said passage opening toward the opposite end of the cylinder and a supplemental inlet valve to supply the deficiency in liquid passing through said passage.

WILLIAM T. STEPHENS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 661,784 Allen Nov. 13, 1900 740,771 McIntyre Oct. 6, 1903 753,530 Ten Eyck Mar. 1, 1904 833,457 Hammond Oct. 16, 1906 893,851 Leyner July 21, 1908 1,396,494 Wright Nov. 8, 1921 1,680,536 Gensmer Aug. 14, 1928 1,781,404 McNab Nov. 11, 1930 

